competitive etiquette

Question - what is good competitive etiquette?

Well I work alongside other businesses in the same sector as me, both locally and further afield. We all get on great and I respect these guys. I won't do anything to these folks or their business that would be considered foul play or dirty pool. I am happy to seek help from these guys and to try to do my best to help them if I can. I feel it’s only fair and I know there is plenty of business for all of us so I am happy and they are happy.

But the thing I am debating over just now is what good competitive etiquette is? For example is it the done thing to ask someone at a networking meeting who their suppliers are? To say well I’m starting a business doing the same or something similar thing can you tell me what do I do as I can’t find anything online about it? I couldn't do it to someone I didn't know, I’d even struggle to do it to someone I did know, and only then I would have to really know them and hope they trusted me enough to not abuse anything they told me.

This isn't really much advice or a huge revelation I’ve had, this is just something I’m pondering.... any thoughts?